Synthesis of organic oxygencontaining compounds



Patented Dec. 9, 1947 UNITED STATES PATENT OFFICE SYNTHESIS OF ORGANIC OXYGEN- CONTAINING COMPOUNDS No Drawing. Application May 17, 1946, Serial No. 670.526

7 Claims. 1

This invention relates to the synthesis of organic oxygen-containing compounds and more particularly to the preparation of carboxylic acids by the interaction of poly-alkylene cyclic monoethers with carbon monoxide and water in the presence of specific catalysts as hereinafter set forth.

The reaction of dialkyl ethers with carbon monoxide to form carboxylic esters or acids has been known for several years. The Larson patent, U. S. 2,135,450, issued November 1, 1938, discloses that carbon monoxide reacts with aliphatic ethers in the presence of condensation catalysts such as metal and non-metal halides to form carboxylic esters; promoters such as powdered nickel, nickel oxide, etc, could be introduced to promote the activity of the condensing agent. The Gresham patent. U. S. 2,364,438, issued December 5, 1944, discloses the reaction between the cyclic diethers, especially the cyclic Iormals. and carbon monoxide in the presence of acidic catalysts such as boron fluoride and the like. It also has been disclosed heretofore that the reaction between dialkyl ethers and carbon monoxide in the presence of condensing agents may be directed to the formation of carboxylic acids by including water in the reaction mixture (Loder, U. S. 2,135,453). In general, however, the processes heretofore disclosed could not be employed satisfactorily with the polyalkylene cyclic monoethers, which were very difiicult to hydrolyze, and which were less reactive to carbon monoxide than were the cyclic formals. Moreover, the cyclic ethers other than the formals tended to yield tarry products under the reaction conditions required for introduction of carbon monoxide. It has been observed, as disclosed in copending applications. S. N. 590,311, filed April 25, 1945, and S. N. 593,333, filed May 11, 1945, that nickel and cobalt are highly active catalysts for certain carboxylaton reactions, e. g., the introduction of carbon monoxide into vinyl ethers and esters to form acrolein, and the introduction of carbon monoxide into oleflne-aminc mixtures to form amides. In contrast with these prior processes the present invention is directed to the reaction of a cyclic monoether, such as tetrahydrofuran, with water and carbon monoxide in the presence of nickel carbonyl, which in certain embodiments is promoted with a metal halide. Recently it has been reported that experiments on carboxylation of tetrahydrofuran with similar catalysts also have been in progress in Germany (Chemical and Engineering News, vol. 23, No. 17, September 10, 1945).

An object of this invention is to provide an improved process for the preparation of aliphatic monocarboxylic and dlcarboxylic acids. Another object of the invention is to provide a process for the synthesis of monocarboxyllc acids having 5 carbon atoms per molecule. A further object is to provide a method for the synthesis of adipic acid from relatively simple and inexpensive starting materials. Other objects and advantages of the invention will appear hereinafter.

It has been discovered in accordance with this invention that polyalkylene cyclic monocthcrs (trimethylene oxide, tetrahydroiuran, pentamethylene oxide, etc.) react with carbon monoxide and water in the presence of nickel carbonyl, which, in general. is employed in combination with a promoter such as a nickel halide or other metal halide as set forth hereinafter, to form allphatic carboxylic acids. In general, the reaction between the cyclic ether. carbon monoxide. and water is conducted in accordance with the invention under pressures of about 50 to 3000 atmospheres, preferably about 400 to 1200 atmospheres. The reaction temperature is generally maintained within the range of about to 400 C., preferably about 250 to 350 C.

The catalyst which is employed in the practice of the invention is preferably nickel tetracarbonyl having the empirical formula NiICOh, but other similar carbonyls such as nickel carbonyl hydride, or hydrates thereof, may be employed if desired. The preferred combination of catalyst and promoter is a mixture of nickel carbonyl and a nickel halide such as nickel chloride or nickel iodide. In general auxiliary catalysts, or promoters, which may be employed simultaneously with nickel carbonyl include platinum, iodine, and the metal halides, such as zlnc halides, copper halides, gold halides, platinum halides, and the like.

The nature of the reaction product obtained by the reaction between tetrahydrofuran, carbon monoxide and water in accordance with the invention depends to a certain extent upon the catalyst which is employed. Under certain conditions illustrated in the examples the chief product formed by the reaction is a monocarboxylic acid having 5 carbon atoms per molecule. It appears that the yield of dicarboxylic acids, such as adipic acid, is improved by the suppression of certain side reactions involving carbon monoxide and water, and that such increased yields are achieved by the avoidance of any substantial trace of catalyst for the said side reaction. Accordingly, dicarboxylic acids, such as adipic acid are formed from tetrahydrofuran. carbon monoxide, and water in the presence of nickel carbonyl in improved yields when precautions are taken to avoid corrosion of the reaction vessel, which might result in the contamination of the reaction mixture with traces of undesirable catalytic materials.

The invention is illustrated further by means of the following examples.

Example 1.- A reaction mixture containing 23.8 grams of NlCl2fiH2O, 17.1 grams of NHCOM, 72.1 grams of tetrahydroiuran and 70.3 grams of water was heated in a copper-lined shaker tube at a temperature of 290 to 315 C. with carbon monoxide under a pressure of 740 to 800 atmospheres. The resulting mixture was Withdrawn from the reaction vessel, and the ether-soluble portion thereof was fractionated in a still equipped with an efiicient fractionating column. The main product, weight 31.9 grams, was an acid fraction having a, boiling pont of about 75 to 97 C. at 28 to 29 mm. A relatively smaller quantity. weight 17.8 grams, of higher boiling material, B P. up to 131" C. at 1 mm. also was collected. There remained in the reaction vessel 6.4 grams of a solid acidic material. The ma n fraction had a neutralization equ valent of 106 (theory for n-valeric ac d or methi lct ylacetic acid, 102.1). Redistillation of this fraction resolved it into methylethylacet c acid (B. P. 70 to 73 C. at 18 mm.; refractive index: 1.4011 at 25/D; freezing below -78 0., neutral equivalent, 102) and n-valeric acid (B. P. 77 to 80 C. at 10 mm.: refractive index:1.4093 at 25/D: neutral equivalent, 3).

Example 2.A mxture containirg 10.0 grams of nick l carbonyl. 5 grams of ZnCl 9 grams of water, 36 1 grams of tetrahydrofuran and 65 c. c. of cyclohexane wa heated inacoDD tube for 1 hour at a temperature of 310 to 330 C. under a carbon monoxide pressure of 600 to 840 atmospheres. Distillation of the reaction mixture gave 9 4 grams of a distillate having two layers, B. P. 41 to 63 C. at 100 mm. The upper layer of this fraction consisted chiefly of aliphatic monocarboxylic acids.

Example 3.A mixture containing 72.0 grams of terahydrofuran, 36 grams of water, 3.5 grams of NiClaGHzO, 2.1 grams of 12 and 5.9 grams of Ni(CO)4 was heated in a shaker tube for four hours with carbon monoxide under a pressure of 200 atmospheres at a tem"erature of 260 to 300 C., and for an additional 0.5 hour at 500 to 700 atmospheres pressure. The product was removed irom the reaction vessel, after which the said vessel was washed with water and the washings added to the reaction product. The aqueous layer was withdrawn from the resulting mixture and was extracted with benzene. The extract thus obtaincd was combined with the upper layer, and the mixture was distilled yielding a high boiling acid fraction (evidently containing Valerie acid, methylcthylacetic acid and micro]- actone) which corresponded to the conversion of 25.2% based on the amount of tetrahydrofuran initially present.

Example 4.-Example 3 was repeated except that the reaction mixture also contained 1.0 gram BiCla, and 10 grams of finely divided quartz; this mixture was heated for four hours at 298 to 304 C. under a carbon monoxide pressure of 280 to 410 atmospheres. Distillation of the resulting product gave C acids and lactones in 31% conversion, based on the amount of tetrahydroi'uran initially present.

Example 5.-A mixture containing 72.1 grams of tetrahydrofuran, 36 grams of water, 3 grams of NiCl2.6H2O, 3 grams I2, 5 grams of platinfzed asbestos (5% Pt), and 5 grams of Ni(CO)4 was 4 heated in a stainless steel shaker tube with carbon monoxide under a pressure of 265 to 320 atmospheres at a temperature of 280. to 320 C. for minutes. The resulting product was withdrawn from the reaction vessel and the vessel was thereafter washed with methanol. Distillation of the washings and reaction product gave 46 grams of product bcilirg in the range of mzthyleihylacetic acid and 3.4 grams of an oily sol d boiling at about to C. under a pressure of 5 mm. The latter was washed with ether, which caused the separation of white crystalline material, M. P., 146 to 150 C., which was identified as adipic acid by mixed melting point with an authentic sample.

It is to be understood that the above cxanr'les are illustrative only. and that numerous methods may be employed for practicing the invention. For example. the solid acidic residue, cbtained after the distillation of the C5 acids may be purified by fractional crystallization, whereby the adipic acid may be purified. Moreover, the acidic reaction nroductsmay be csterificd by reaction with an alcohol, and the resultin esters may be separated from the mixture by careful distillation. If desired, the reaction between tetrahydrofuran, carbon monoxide and water may be carried out in a continuous manner; e. by passing the tetrahydrofuran and water through a tubu'ar converter either cocurrently or countercuriently to a flow of carbon monoxide, the rates of flow being adjusted coordinately with pressure, temperature, and catalyst to yield the desired degree of reaction.

The reaction may be conducted in vessels made of or lined with silver, chromium, stainless steel, platinum, copper, and the like, or refractory materials such as glass. silica, porcelain, etc.

The monocarboxylic acids obtained in accordance with the invention are widely useful per se, and are especially valuable in the form of their esters as solvents, plastic'zers, etc. The dcarboxylic acids, especially adipic acid, are of Considerable value as an intermediat in the manufacture of nylon-type resins.

It is to be understood that many changes may be made in the details illustrated herein, without departing from the scope of the invention or sacrificing any of the advantages that may be derived therefrom.

Iclaim:

1. A process for the synthesis of carbox lie acids which comprises reacting a polyalkylene cyclic mono-ether with carbon monoxide in the presence of a nickel carbonyl catalyst at a temperature of about 150 to 400 C. under a pressure of 50 to 3000 atmospheres, and thereafter separating from the resulting mixture the monomeric carboxylic acids produced by the resulting reaction.

2. A process for the synthesis of carboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature within the range of about 150 to 400 C. under a pressure of about 50 to 300 atmospheres in the presence of a nickel carbonyl catalyst and thereafter separating from' the resulting mixture the monomeric carboxylic acids produced by the resulting reaction.

3. A process for the synthesis of carboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature within the range of about 150 to 400 C. under a pressure of about 400 to 1200 atmospheres in the presence of a nickel carbonyl catalyst and thereafter separating from the resulting mixture the monomerc carboxylic acids produced by the resulting reaction,

4. A process for the synthesis of carboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature within the range of about 150 to 400 C. under a pressure of about 400 to 1200 atmospheres in the presence of a nickel carbonyl catalyst and a metal halide promoter and thereafter separating from the resulting mixture the monomeric carboxylicacids produced by the resulting reaction.

5. A process for the synthesis of carboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature within the range of about 150 to 400 C. under a pressure of about 400 to 1200 atmospheres in the presence of a nickel carbonyl catalyst and iodine as a promoter and thereafter separating from the resulting mixture the monomeric carboxylic acids produced by the resulting reaction.

6. A process for the synthesis of monocarboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature of about 250 to 350 C. under a pressure of about 400 to 1200 atmospheres in the presence or a nickel carbonyl catalyst and thereafter distilling from the resulting mixture, as

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,135,450 Larson Nov. 1, 1938 2,135,451 Loder Nov. 1, 1938 2,273,785 Larson Feb, 17, 1942 2,364,438 Gresham Dec. 5, 1944 OTHER REFERENCES Chem. and Engineering News, vol. 23, No. 17, page 1517; Sept. 10, 1945.

Certificate of Correction Patent No. 2,432,474.

December 9, 1947.

WILLIAM F. GRESHAM It is hereby certified that errors appear in the (printed specification of the above numbered patent reguiring correction as follows:

C'.,;l1ne 39, for 9 claim 2, for "300 read 3000; and that the said Letters Patent should be read with 78 (3.," read olumn 3, line 29, Example 1, for

4 grams read 9.4 grams; column 4, line 65,

these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 17th day of February, A. D. 1948.

THOMAS F. MURPHY,

Assistant Omissions of Patents.

thereafter separating from the resulting mixture the monomerc carboxylic acids produced by the resulting reaction,

4. A process for the synthesis of carboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature within the range of about 150 to 400 C. under a pressure of about 400 to 1200 atmospheres in the presence of a nickel carbonyl catalyst and a metal halide promoter and thereafter separating from the resulting mixture the monomeric carboxylicacids produced by the resulting reaction.

5. A process for the synthesis of carboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature within the range of about 150 to 400 C. under a pressure of about 400 to 1200 atmospheres in the presence of a nickel carbonyl catalyst and iodine as a promoter and thereafter separating from the resulting mixture the monomeric carboxylic acids produced by the resulting reaction.

6. A process for the synthesis of monocarboxylic acids which comprises reacting tetrahydrofuran with carbon monoxide and water at a temperature of about 250 to 350 C. under a pressure of about 400 to 1200 atmospheres in the presence or a nickel carbonyl catalyst and thereafter distilling from the resulting mixture, as

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,135,450 Larson Nov. 1, 1938 2,135,451 Loder Nov. 1, 1938 2,273,785 Larson Feb, 17, 1942 2,364,438 Gresham Dec. 5, 1944 OTHER REFERENCES Chem. and Engineering News, vol. 23, No. 17, page 1517; Sept. 10, 1945.

Certificate of Correction Patent No. 2,432,474.

December 9, 1947.

WILLIAM F. GRESHAM It is hereby certified that errors appear in the (printed specification of the above numbered patent reguiring correction as follows:

C'.,;l1ne 39, for 9 claim 2, for "300 read 3000; and that the said Letters Patent should be read with 78 (3.," read olumn 3, line 29, Example 1, for

4 grams read 9.4 grams; column 4, line 65,

these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 17th day of February, A. D. 1948.

THOMAS F. MURPHY,

Assistant Omissions of Patents. 

